In a conventional reinforcing bar binder, a wire reel around which a wire is wound is retained at the rear portion thereof and, when the switch is turned on and a trigger is manipulated, the wire is drawn out and fed forward from the wire reel through a wire feeding device, discharged in a loop shape from the tip end curved portion of a guide arm and wound onto a reinforcing bar and, thereafter, a twisting hook grips a portion of the loop and torsionally rotates to bind the reinforcing bar. As a configuration for automatically adjusting the wire twisting torque of such a reinforcing bar binder, there has been a configuration which provides displaying means for displaying the type of a wire on the side surface of a wire reel, employs detecting means provided on the reinforcing bar binder for detecting the displaying means, identifies the type of the wire on the basis of the result of detection from the detecting means and automatically adjusts the twisting torque, as disclosed in JP-B No. 3050369.
A conventional reinforcing bar binder employs reflective stickers as the displaying means and a plurality of photo sensors as the detecting means so that any of the plural sensors can detect the reflective stickers provided on the side surface of the wire reel to detect the type of the wire reel. However, such a reinforcing bar binder requires plural photo sensors, thus involving a complicated and expensive construction. Furthermore, the reflective stickers may be detected by photo sensors other than the photo sensors used for detecting the reflective stickers, due to the rotation speed of the wire reel and external disturbing light and the like, which has caused malfunctions in some cases.
The present invention was made in view of the aforementioned problems. It is a first object of the present invention to provide a reinforcing bar binder capable of certainly identifying the type of a wire reel and automatically adjusting the amount of feeding of the wire wound around the wire reel or the twisting torque on the wire while having a simple and inexpensive construction. Further, it is a second object to provide a wire reel used with the reinforcing bar binder. Further, it is a third object to provide a method for certainly identifying a wire reel.